Occurrence of extended spectrum β-lactamaseand AmpC-producing Escherichia coli in meat samples

The aim of the study was a preliminary determination of occurrence of extended spectrum β-lactamases (ESBL)- and AmpC-producing Escherichia coli (E.coli) in raw meat samples collected from slaughter-houses located in different regions of Poland. A total of 141 samples were tested, comprising 78 pork samples, 44 beef samples, and 19 chicken meat samples. Isolated and identified E. coli strains were examined for the ESBL and/or AmpC β-lactamases production by the use of four disc diffusion and minimum inhibitory concentration tests. All strains positive in one or both tests were examined by PCR for the presence of the bla_CTX, bla_TEM, bla_SHV, and bla_{CMY-2 group} genes. During the study, 154 E. coli strains were isolated from 95 samples. Among these, 18 (11.7%) strains were identified in phenotypic tests as ESBL-producing and seven (4.5%) strains as AmpC-positive. The presence of the genes encoding selected ESBL-s (TEM, CTX, SHV) was identified in 14 of the strains recognised as ESBLpositive in phenotypic tests. All AmpC-positive isolates showed the presence of the CMY-2 group encoding genes. One of these strains had also the CTX-M and TEM genes, and four of them expressed the TEM marker.